In recent years, fingerprint authentication has been attracting attention as one of authentication methods for identifying an individual. Fingerprints differ person to person and have a feature that does not change even though years have passed. Thus, fingerprint authentication is considered having higher reliability than currently prevailing password authentication and the like. Meanwhile, in fingerprint authentication, it is necessary to prevent wrongdoing that someone impersonates another person using a fake finger forged using another person's fingerprint. As techniques for preventing such wrongdoing, for example, Patent Documents 1 and 2 disclose techniques of detecting a fake finger based on a color of a surface of a finger irradiated with light.
Patent Document 1: Patent Publication JP-A-2003-50993
Patent Document 2: Japanese Patent Publication No. 2637253
However, in Patent Documents 1 and 2, since a fake finger is detected based on a color of a surface of a finger, a fake finger made such that a transparent or flesh-colored thin film duplicated from another person's fingerprint is attached to a surface of a finger is hardly discriminated. Particularly, a fake finger with a transparent thin film attached thereto is hardly discriminated since a color of a fake finger surface assimilates with a color of a skin.